// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#include "draco/core/decoder_buffer.h"

#include "draco/core/macros.h"
#include "draco/core/varint_decoding.h"

namespace draco {

    DecoderBuffer::DecoderBuffer()
        : data_(nullptr),
        data_size_(0),
        pos_(0),
        bit_mode_(false),
        bitstream_version_(0) {}

    void DecoderBuffer::Init(const char *data, size_t data_size) {
        Init(data, data_size, bitstream_version_);
    }

    void DecoderBuffer::Init(const char *data, size_t data_size, uint16_t version) {
        data_ = data;
        data_size_ = data_size;
        bitstream_version_ = version;
        pos_ = 0;
    }

    bool DecoderBuffer::StartBitDecoding(bool decode_size, uint64_t *out_size) {
        if (decode_size) {
#ifdef DRACO_BACKWARDS_COMPATIBILITY_SUPPORTED
            if (bitstream_version_ < DRACO_BITSTREAM_VERSION(2, 2)) {
                if (!Decode(out_size)) {
                    return false;
                }
            } else
#endif
            {
                if (!DecodeVarint(out_size, this)) {
                    return false;
                }
            }
        }
        bit_mode_ = true;
        bit_decoder_.reset(data_head(), remaining_size());
        return true;
    }

    void DecoderBuffer::EndBitDecoding() {
        bit_mode_ = false;
        const uint64_t bits_decoded = bit_decoder_.BitsDecoded();
        const uint64_t bytes_decoded = (bits_decoded + 7) / 8;
        pos_ += bytes_decoded;
    }

    DecoderBuffer::BitDecoder::BitDecoder()
        : bit_buffer_(nullptr), bit_buffer_end_(nullptr), bit_offset_(0) {}

    DecoderBuffer::BitDecoder::~BitDecoder() {}

}  // namespace draco
